It's weird about deer. I heard one guy say that looking up had been "bred into the deer' which is impossible, but still you wonder if certain genetic qualities that cause a deer to look up have allowed those features to proliferate due to hunting pressure. We know acquired characteristics cannot be inhereted, but other characteristics could be, or maybe they are taught like LBR says. Their natural predators certainly never brought death from above.

Vector yes, I never thought about that. I was using simple rates of change and an equation I got from a physic textbook about gravity to make my graphical model, but that makes it alot easier. That's why I'm not a math major I guess.